|Carbon D. Metric|
I remember when I was a wee boy I set up my first trip trap. Definitely a natural 20. Caught another running kid, as he went down a hill path and through foliage so they could not see the vine. Tripped them down a rocky hill into some more rocks; the offending trip-vine did its work then flung itself into the bush, nothing to see here.
So yeah, that might be something a player with one rank and all natural materials could do.
You would want/need:
1) The Cunning Trigger and Quick Trapsmith rogue talents.
2) Plentiful downtime to make traps.
3) A bag of holding for all of your traps.
4) The ability to w/o fail scout around / sneak to lay out your traps and "set up the battlefield" so to speak. The invisibility spell is excellent here, as it lasts fairly long and only breaks if you attack, not if some idiot steps on your trap that you previously set. Silence spell is also helpful, though PF nerfed the duration to rounds/level, so it's unlikely to be practical to use.
5) A DM willing to let you use your particular skills and talents to scout ahead and lay out the traps, and a play group willing to sit around while that's adjudicated.
Using traps is tough as a PC. You're always being proactive and exploring/attacking/invading. Never defending, really.